On 01/28/21 18:31, Valentin Schneider wrote: > Rik noted a while back that a handful of > > sd->flags & SD_ASYM_CPUCAPACITY > > & family in the CFS load-balancer code aren't guarded by the > sched_asym_cpucapacity static branch. > > The load-balancer is already doing a humongous amount of work, but turning > those checks into NOPs for those who don't need it is fairly > straightforward, so do that. > > Suggested-by: Rik van Riel <[email protected]> > Signed-off-by: Valentin Schneider <[email protected]> > ---
Reviewed-by: Qais Yousef <[email protected]> Thanks -- Qais Yousef > kernel/sched/fair.c | 11 ++++++----- > kernel/sched/sched.h | 6 ++++++ > 2 files changed, 12 insertions(+), 5 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 0f6a4e58ce3c..7d01fa0bfc7e 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -8465,7 +8465,7 @@ static inline void update_sg_lb_stats(struct lb_env > *env, > continue; > > /* Check for a misfit task on the cpu */ > - if (env->sd->flags & SD_ASYM_CPUCAPACITY && > + if (sd_has_asym_cpucapacity(env->sd) && > sgs->group_misfit_task_load < rq->misfit_task_load) { > sgs->group_misfit_task_load = rq->misfit_task_load; > *sg_status |= SG_OVERLOAD; > @@ -8522,7 +8522,8 @@ static bool update_sd_pick_busiest(struct lb_env *env, > * CPUs in the group should either be possible to resolve > * internally or be covered by avg_load imbalance (eventually). > */ > - if (sgs->group_type == group_misfit_task && > + if (static_branch_unlikely(&sched_asym_cpucapacity) && > + sgs->group_type == group_misfit_task && > (!group_smaller_max_cpu_capacity(sg, sds->local) || > sds->local_stat.group_type != group_has_spare)) > return false; > @@ -8605,7 +8606,7 @@ static bool update_sd_pick_busiest(struct lb_env *env, > * throughput. Maximize throughput, power/energy consequences are not > * considered. > */ > - if ((env->sd->flags & SD_ASYM_CPUCAPACITY) && > + if (sd_has_asym_cpucapacity(env->sd) && > (sgs->group_type <= group_fully_busy) && > (group_smaller_min_cpu_capacity(sds->local, sg))) > return false; > @@ -8728,7 +8729,7 @@ static inline void update_sg_wakeup_stats(struct > sched_domain *sd, > } > > /* Check if task fits in the group */ > - if (sd->flags & SD_ASYM_CPUCAPACITY && > + if (sd_has_asym_cpucapacity(sd) && > !task_fits_capacity(p, group->sgc->max_capacity)) { > sgs->group_misfit_task_load = 1; > } > @@ -9419,7 +9420,7 @@ static struct rq *find_busiest_queue(struct lb_env *env, > * Higher per-CPU capacity is considered better than balancing > * average load. > */ > - if (env->sd->flags & SD_ASYM_CPUCAPACITY && > + if (sd_has_asym_cpucapacity(env->sd) && > capacity_of(env->dst_cpu) < capacity && > nr_running == 1) > continue; > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > index 045b01064c1e..21bd71f58c06 100644 > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -1482,6 +1482,12 @@ DECLARE_PER_CPU(struct sched_domain __rcu *, > sd_asym_packing); > DECLARE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity); > extern struct static_key_false sched_asym_cpucapacity; > > +static inline bool sd_has_asym_cpucapacity(struct sched_domain *sd) > +{ > + return static_branch_unlikely(&sched_asym_cpucapacity) && > + sd->flags & SD_ASYM_CPUCAPACITY; > +} > + > struct sched_group_capacity { > atomic_t ref; > /* > -- > 2.27.0 >
